Re: [PATCH 2/2] configs: Add generic qcom_tfa_optee_defconfig

Casey Connolly
2026-01-16T17:46:24Z

Hi Sumit,

(Top-posting since this thread is getting a bit busy)

I'm not sure if Neil and I properly conveyed why we don't agree with
your proposal here: essentially it is an inversion of logic.
CONFIG_OPTEE doesn't indicate that the board IS running OP-TEE, it just
builds in support for OP-TEE. In general U-Boot is trying to trend away
from using kconfig to dictate behaviour in this way.

Adjacently, for Qualcomm support in U-Boot we are trying to improve upon
the status quo: we don't do board-specific code, we limit hardcoding
functionality or build-time configuration in favour of runtime checks as
much as possible.

With that perspective in mind, I would much prefer that switching from
QTEE to TF-A/OP-TEE on the rb3gen2 (or any other qcom board) not require
flashing a bespoke U-Boot build, the same build should just work on both.

There are several ways it might be possible to check for OP-TEE at
runtime, arguably the simplest is the SMC call I proposed (which could
be restricted to just kodiak), the other idea that comes to mind is
populating the x2 register with a magic number when jumping to U-Boot,
or even using the functionality already in place for passing data
between bootloader stages (assuming the necessary bits are upstream in
both projects).

You say that making that SMC call on QTEE is undefined behaviour, but
surely it doesn't break stuff? I'd hope that simply seeing what happens
would be enough to define it, maybe checking with the boot team too.

Your patch also mentions the EFI DT fixup protocol, but there is no
corresponding code for that. iirc there are other DT changes needed for
everything to work properly on rb3gen2 with OP-TEE, is the plan to get
those changes done in such a way that the same DT will work with both
OP-TEE and QTEE?

- Casey

On 1/16/26 13:17, Sumit Garg wrote:
> On Fri, Jan 16, 2026 at 10:53:15AM +0100, Neil Armstrong wrote:
>> On 1/16/26 08:53, Sumit Garg wrote:
>>> On Fri, Jan 16, 2026 at 08:34:33AM +0100, Neil Armstrong wrote:
>>>> On 1/16/26 07:57, Sumit Garg wrote:
>>>>> On Thu, Jan 15, 2026 at 02:35:23PM +0100, Neil Armstrong wrote:
>>>>>> On 1/15/26 14:27, Sumit Garg wrote:
>>>>>>> On Thu, Jan 15, 2026 at 02:03:29PM +0100, Neil Armstrong wrote:
>>>>>>>> On 1/15/26 13:25, Sumit Garg wrote:
>>>>>>>>> + Jens (OP-TEE driver author in U-Boot)
>>>>>>>>>
>>>>>>>>> On Thu, Jan 15, 2026 at 11:49:49AM +0100, neil.armstrong@linaro.org wrote:
>>>>>>>>>> On 1/15/26 07:10, Sumit Garg wrote:
>>>>>>>>>>> On Wed, Jan 14, 2026 at 03:56:02PM +0100, Casey Connolly wrote:
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> On 09/01/2026 12:02, Sumit Garg wrote:
>>>>>>>>>>>>> On Thu, Jan 08, 2026 at 05:41:42PM +0100, Casey Connolly wrote:
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> On 29/12/2025 12:43, Sumit Garg wrote:
>>>>>>>>>>>>>>> From: Sumit Garg <sumit.garg@oss.qualcomm.com>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Recently upstream TF-A/OP-TEE has started gaining support for Qcom
>>>>>>>>>>>>>>> platforms. RB3Gen2 being the first one and more to come. U-Boot in
>>>>>>>>>>>>>>> corresponding boot flow is packaged as a position independent executable.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> So, lets add a generic U-Boot defconfig for Qcom platforms to support
>>>>>>>>>>>>>>> TF-A/OP-TEE based TrustZone stack. Build command:
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> $ make qcom_tfa_optee_defconfig
>>>>>>>>>>>>>>> $ make -j`nproc` DEVICE_TREE=qcom/qcs6490-rb3gen2
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> This would be better suited as a config fragment rather than a new
>>>>>>>>>>>>>> defconfig imo.
>>>>>>>>>>>>>
>>>>>>>>>>>>> That's fine with me to add it as a config fragment.
>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> But more importantly, enabling OPTEE support in U-Boot doesn't imply
>>>>>>>>>>>>>> that it will be used, just that it's supported.
>>>>>>>>>>>>>
>>>>>>>>>>>>> There are real use-cases of OP-TEE in U-Boot for Qcom platforms like
>>>>>>>>>>>>> secure EFI variables based on OP-TEE secure storage. Have a look here [1].
>>>>>>>>>>>>>
>>>>>>>>>>>>> And sure there will be more such use-cases like fTPM, KASLR etc. can be
>>>>>>>>>>>>> supported based on OP-TEE.
>>>>>>>>>>>>
>>>>>>>>>>>> I was referring literally to the fact that CONFIG_OPTEE being enabled
>>>>>>>>>>>> doesn't imply that OP-TEE is running, it's faulty logic to assume that's
>>>>>>>>>>>> the case and add nodes to the DT.
>>>>>>>>>>>
>>>>>>>>>>> I don't disagree here as having a runtime check is always a better
>>>>>>>>>>> choice then a compile time config option. However, there isn't a common
>>>>>>>>>>> info method from properietary firmware that says if QTEE is running
>>>>>>>>>>> instead of OP-TEE.
>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> I just checked and there is an SMC call that tells you the UUID for the
>>>>>>>>>>>> trusted OS, referred to as OPTEE_SMC_CALL_GET_OS_UUID in U-Boot and
>>>>>>>>>>>> OPTEE_ABI_CALL_GET_OS_UUID in OP-TEE. Presumably this identifies OP-TEE
>>>>>>>>>>>> specifically.
>>>>>>>>>>>
>>>>>>>>>>> Also, we don't know how the QTEE will react to this OP-TEE specific SMC
>>>>>>>>>>> call given it's different variants running on legacy and the newer SoCs.
>>>>>>>>>>> So I would suggest to better gate OP-TEE presence behind a compile time
>>>>>>>>>>> check only.
>>>>>>>>>>
>>>>>>>>>> So you say it's fine to add the optee node, and the driver will bail out if
>>>>>>>>>> OPTEE is not present, but it's not good to call OPTEE_SMC_CALL_GET_OS_UUID
>>>>>>>>>> in the fixup code to enable OPTEE only if present ?
>>>>>>>>>>
>>>>>>>>>> It's literally the same, my point in https://lore.kernel.org/all/b60d5ee7-fa27-4dc1-8a09-964912ec5654@linaro.org/
>>>>>>>>>> was exactly that, just call OPTEE_SMC_CALL_GET_OS_UUID and add the OPTEE
>>>>>>>>>> node only if present _AND_ if CONFIG_OPTEE is enabled.
>>>>>>>>>>
>>>>>>>>>> Move the CONFIG_OPTEE enable in a fragment and we're done, you will only
>>>>>>>>>> select OPTEE explicitly on desired platforms, and won't run the naughty
>>>>>>>>>> OPTEE_SMC_CALL_GET_OS_UUID on old crappy platforms.
>>>>>>>>>
>>>>>>>>> I am still trying to understand what benefit does invoking
>>>>>>>>> OPTEE_SMC_CALL_GET_OS_UUID from platform code provides us. Surely it
>>>>>>>>> can't be used to detect OP-TEE not present when QTEE is running due to
>>>>>>>>> unknown behaviour with QTEE.
>>>>>>>>
>>>>>>>> Sorry but what exactly do you expect that will happen if you enable the OPTEE
>>>>>>>> driver when running with QTEE ?
>>>>>>>
>>>>>>> The OP-TEE SMC calls are not at all supported with QTEE, so the expected
>>>>>>> behaviour is undefined. IOW, the OP-TEE SMC ABI is not compatible with
>>>>>>> QTEE. However, it's going to be hit and trial method to see what QTEE
>>>>>>> responds to OP-TEE SMC calls. So it's not a reliable source of
>>>>>>> information we can use to detect which TEE is present or not.
>>>>>>
>>>>>> So until we know, this change is a no go, we can't just add the /optee node
>>>>>> and hope the person building uboot did the right thing.
>>>>>
>>>>> Not sure why you think Qualcomm platforms are special in this regards
>>>>> when similar OP-TEE node additions based on CONFIG_OPTEE exist for other
>>>>> platforms, see example here [1] [2] [3].
>>>>>
>>>>> The OP-TEE configs will surely be part of a separate config fragment and
>>>>> I can add comments there for developer's awareness.
>>>>>
>>>>> [1] arch/arm/dts/imx8mm-u-boot.dtsi:10
>>>>> [2] arch/arm/dts/imx8mn-u-boot.dtsi:10
>>>>> [3] arch/arm/dts/imx8mp-u-boot.dtsi:11
>>>>>
>>>>>>
>>>>>> I propose an alternate way, is to check for QTEE and then test for OPTEE.
>>>>>
>>>>> There are more combinations rather than just QTEE or OP-TEE as follows:
>>>>> - Older targets have support for QSEECOM
>>>>> - Newer targets with QTEE support
>>>>> - Chrome targets without any TEE support
>>>>> - IoT targets with OP-TEE support
>>>>>
>>>>> Do you have any particular mechanism in mind for detecting OP-TEE
>>>>> presence at runtime? And surely that has to be well supported on variety
>>>>> of SoC where U-Boot is supported as of now.
>>>>
>>>> OPTEE_SMC_CALL_GET_OS_UUID which works fine on like all the other ARM based
>>>> platforms.
>>>
>>> Can you share at-least one example of other Arm based platform where this
>>> SMC call is used to add OP-TEE DT node?
>>
>> AFAIK no other platforms does that, I never said it was a standard thing,
>> I said it would be necessary to avoid messing with the qualcomm proprietary
>> boot chain.
>>
>>>
>>>>
>>>> It's the only way, and only Qualcomm engineers can answer how to determine
>>>> without any risk which TEE is running on the system.
>>>
>>> The fact that you keep ignoring my responses that OP-TEE SMC ABI is not
>>> compatible with QTEE/QSEECOM SMC ABI is not going to change (see [1]).
>>>
>>> I am not sure why it's a blocker to use CONFIG_OPTEE for OP-TEE DT node
>>> addition on Qcom platforms when the same criteria is being used for imx8*
>>> platforms already.
>>
>> It is not, if the node is present the it's fine. I'm concerned by adding
>> the node when CONFIG_OPTEE is enabled.
>>
>> Usually, the ARM64 platforms are shipped with a well-known or compatible
>> boot chain like TF-A, and OPTEE is present or not. Those platforms
>> will add the optee node knowing it can be present, and knowing other TEE
>> won't crash if OPTEE_SMC_CALL_GET_OS_UUID is called.
>>
>> You propose the other way, adding the optee node when config is present,
>> not knowing exactly if the current system has optee or a qualcomm proprietary
>> TEE that could not survive a OPTEE_SMC_CALL_GET_OS_UUID call.
>
> Maybe I should have provided reference to the overall open boot stack [1]
> early which is being planned for IoT platforms to begin with. The PR for
> meta-qcom is here [2]. We are mostly waiting for the OEM only signing
> feature for TZ image to be available in XBL_SEC such that any developer
> can excercise that stack:
>
> PBL (ROM) -> XBL -> TF-A BL2 -> TF-A BL31 -> BL33 -> Linux kernel
> |
> --> OP-TEE as BL32
>
> TF-A and OP-TEE are going to be supported in a similar fashion on Qcom
> platforms as any other ARM64 platform.
>
> [1] https://trustedfirmware-a.readthedocs.io/en/latest/plat/qti/rb3gen2.html
> [2] https://github.com/qualcomm-linux/meta-qcom/pull/1172
>
>>
>> So my suggestion is:
>> - ask the boot team a sequence/way to determine exactly which TEE is loaded (using SMC, smem or whatever)
>> - only add the optee node if OPTEE or a compatible TEE is present
>>
>> Then if CONFIG_OPTEE is enabled & the node is present the driver will
>> be able to communicate with OPTEE.
>
> Hence, OP-TEE is going to be supported in a developer controlled
> environment only like any other ARM64 platform. So there is intention to
> reuse the same workflows here. Since it's an open source boot stack then
> it should be possible to use generic methodology if community comes up
> with that later in future. That's why we should avoid Qcom specifc
> platform code to enable such a feature apart from what others do.
>
> -Sumit
>
>>
>>>
>>> [1] https://lore.kernel.org/all/aWjrLF9DUPTaSA1c@sumit-xelite/.
>>>
>>> -Sumit
>>>
>>>>
>>>> Without this, all this discussions is pointless.
>>>>
>>>>>
>>>>> Also, there is added complexity for targets where the developer can't
>>>>> change the TZ firmware themselves on Qcom SoCs due to QTI signing
>>>>> requirement.
>>>>>
>>>>> -Sumit
>>>>>
>>>>>>
>>>>>> Neil
>>>>>>
>>>>>>>
>>>>>>> -Sumit
>>>>>>>
>>>>>>>>
>>>>>>>>>
>>>>>>>>> Jens,
>>>>>>>>>
>>>>>>>>> Will it be fine with you to expose is_optee_api() from the OP-TEE driver
>>>>>>>>> for the platform code to invoke it independently? Just for the sake of this
>>>>>>>>> discussion in case people still insist on it being the right thing to do.
>>>>>>>>>
>>>>>>>>> -Sumit
>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> Neil
>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> My suggestion would be to make this SMC call if CONFIG_OPTEE is enabled
>>>>>>>>>>>> in qcom_psci_fixup(), compare the UUID and add the node if it matches.
>>>>>>>>>>>
>>>>>>>>>>> That's exactly the first SMC call that U-Boot and Linux OP-TEE driver
>>>>>>>>>>> does to compare the UUID here [1] and bail out of the driver. I don't
>>>>>>>>>>> see a value of a redundant invoke in the Qcom specific platform code.
>>>>>>>>>>>
>>>>>>>>>>> [1] drivers/tee/optee/core.c:823: if (!is_optee_api(pdata->invoke_fn))
>>>>>>>>>>>
>>>>>>>>>>> -Sumit
>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>>>
>>>>>>>>>>>>> [1] lib/efi_loader/efi_variable_tee.c
>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> So I think the more appropriate patch here would be to just enable
>>>>>>>>>>>>>> OP-TEE in qcom_defconfig (assuming the binary size isn't significantly
>>>>>>>>>>>>>> affected).
>>>>>>>>>>>>>
>>>>>>>>>>>>> The OP-TEE driver in U-Boot itself is probed based on DT and it's not
>>>>>>>>>>>>> only specific to Qcom platforms but every other platform using OP-TEE.
>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Considering the other patch is based on this assumption that if OP-TEE
>>>>>>>>>>>>>> support is enabled then the board must be using it, a different approach
>>>>>>>>>>>>>> is definitely needed.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Yeah that's true even with TF-A boot flow, there is possibility to boot
>>>>>>>>>>>>> without OP-TEE as well. However, TF-A generally doesn't provide a
>>>>>>>>>>>>> generic option to detect whether OP-TEE is running or not.
>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> When I was looking into this last year I remember discussing this same
>>>>>>>>>>>>>> issue from the Linux side, there is a good argument to be made that
>>>>>>>>>>>>>> OP-TEE support in Linux shouldn't be based on the devicetree -
>>>>>>>>>>>>>> particularly in the Qualcomm case where whether or not OP-TEE is used is
>>>>>>>>>>>>>> a simple software change, nothing to do with hardware.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Sadly it's true for every other silicon vendor too. But OP-TEE support
>>>>>>>>>>>>> based on DT has become an ABI unless migration for OP-TEE support based
>>>>>>>>>>>>> on FF-A comes into picture.
>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> So in general I'm not particularly keen on this approach, I think it
>>>>>>>>>>>>>> /might/ be acceptable for U-Boot to have some fixup code to add the
>>>>>>>>>>>>>> OP-TEE node if OP-TEE is in use with the idea of phasing that out in
>>>>>>>>>>>>>> favour of runtime detection in the OS itself. I'd also expect that fixup
>>>>>>>>>>>>>> code to go in the generic U-Boot DT fixup code that runs before we jump
>>>>>>>>>>>>>> to the OS (like the EFI DT fixup function).
>>>>>>>>>>>>>
>>>>>>>>>>>>> The EFI DT fixup code is already there based on U-Boot DT. Have a look
>>>>>>>>>>>>> here:
>>>>>>>>>>>>>
>>>>>>>>>>>>> boot/image-fdt.c:627: fdt_ret = optee_copy_fdt_nodes(blob);
>>>>>>>>>>>>>
>>>>>>>>>>>>> In general on Arm platforms there isn't any SMC bus to detect
>>>>>>>>>>>>> dynamically if there is support for OP-TEE or not. That's why
>>>>>>>>>>>>> platform bus was choosen for the U-Boot and Linux OP-TEE driver. It's
>>>>>>>>>>>>> similar to how we have the SCM DT node for Qcom platforms.
>>>>>>>>>>>>>
>>>>>>>>>>>>> FF-A bus tries to solve that problem to unify that approach for future
>>>>>>>>>>>>> platform but U-Boot hasn't yet gained support for FF-A based OP-TEE
>>>>>>>>>>>>> driver too.
>>>>>>>>>>>>>
>>>>>>>>>>>>> Anyhow, this is the sanest way I can come up with to enable OP-TEE
>>>>>>>>>>>>> support in a general way for all the Qcom platforms. This is aligned
>>>>>>>>>>>>> with how OP-TEE support is detected for other silicon vendors too.
>>>>>>>>>>>>>
>>>>>>>>>>>>> -Sumit
>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Kind regards,
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> For more information refer here:
>>>>>>>>>>>>>>> https://trustedfirmware-a.readthedocs.io/en/latest/plat/qti/rb3gen2.html
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Signed-off-by: Sumit Garg <sumit.garg@oss.qualcomm.com>
>>>>>>>>>>>>>>> ---
>>>>>>>>>>>>>>> configs/qcom_tfa_optee_defconfig | 7 +++++++
>>>>>>>>>>>>>>> 1 file changed, 7 insertions(+)
>>>>>>>>>>>>>>> create mode 100644 configs/qcom_tfa_optee_defconfig
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> diff --git a/configs/qcom_tfa_optee_defconfig b/configs/qcom_tfa_optee_defconfig
>>>>>>>>>>>>>>> new file mode 100644
>>>>>>>>>>>>>>> index 00000000000..c398521770f
>>>>>>>>>>>>>>> --- /dev/null
>>>>>>>>>>>>>>> +++ b/configs/qcom_tfa_optee_defconfig
>>>>>>>>>>>>>>> @@ -0,0 +1,7 @@
>>>>>>>>>>>>>>> +# Configuration for building a generic U-Boot image
>>>>>>>>>>>>>>> +# with support for TF-A/OP-TEE based Arm TrustZone stack.
>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>> +#include "qcom_defconfig"
>>>>>>>>>>>>>>> +
>>>>>>>>>>>>>>> +CONFIG_TEE=y
>>>>>>>>>>>>>>> +CONFIG_OPTEE=y
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> --
>>>>>>>>>>>>>> // Casey (she/her)
>>>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> --
>>>>>>>>>>>> // Casey (she/her)
>>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>
>>>>>>
>>>>
>>